In fact, tightening of a clamp on a flexible hose causes creeping of the material constituting it, particularly if said hose is subjected to relatively extensive variations in temperature. This may result in the force of tightening decreasing, due to a reduction, even slight, of the diameter of the hose at the spot where the clamp is tightened. Risks of loss of tightness of the seal are then to be feared, the consequences of which may be particularly serious on certain equipment, particularly on automobile vehicles.
On the other hand, it is sometimes essential that the use of the clamps in question does not lead to too considerable efforts on the hose to be tightened, of which the diameter may vary within certain limits. It is therefore desirable that the clamps comprise means for limiting the tightening effort upon assembly on a flexible hose whose diameter attains the upper limit of the tolerances admitted.
A solution to the problems which have just be set forth has already been proposed particularly by Patent No. FR-A-2 470 275, which provides in the band constituting the clamp, at least one corrugation extending over the whole width of the band and projecting outwardly.
This corrugation, combined with a suitable rigidity of the metal constituting the clamp, gives the latter, after assembly and tightening thereof on a flexible hose, the capacity to elastically deform its periphery in the sense of reducing its length, thus enabling it to adapt itself to a reduction of the outer periphery of the hose whilst conserving a sufficient tightening force thereon.
In addition, at the moment of assembly, the corrugation limits the tightening force which is exerted on the periphery of the hose.
However, the solution proposed is not entirely satisfactory, in particular if it is impossible to place between the corrugation and the flexible hose to be tightened a strip of metal ensuring the continuity of the tightening effort over the whole periphery of the hose.